Lyman-Alpha Time Series Updated

October 29, 2007

The composite Lyman-alpha time series has been updated to include the latest versions of the TIMED SEE and SORCE SOLSTICE solar irradiance measurements of the bright H I 121.5 nm emission. These TIMED and SORCE data are used in the 2003-present time range and are scaled to match the UARS reference level as discussed by Woods et al. [JGR, 2000]. The composite time series goes back to 1947 using a combination of measurements and modeling results, all referenced to the UARS reference level.

In addition to the new TIMED and SORCE data, the composite Lyman-alpha time series has been updated in the 2001-2003 time frame with just model results. There are some measurements during that time from UARS and TIMED, but degradation issues for both of those instruments in the 2001-2003 time period need to be addressed first.

The composite Lyman-alpha time series is updated daily and available from the SEE website ( and also from the LASP Interactive Solar Irradiance Datacenter (LISIRD) (

Composite Lyman-Alpha Graph

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